Renjie Deng,Kuiyi You,Wenjin Ni,Fangfang Zhao,Pingle Liu,He’an Luo
In this work, we developed a low-temperature and efficient approach for the highly selective preparation of valuable p -nitrochlorobenzene from the liquid-phase catalytic nitration of chlorobenzene with NO 2 in O 2 -Ac 2 O-Hβ composite system. The results demonstrated that the introduction of molecular oxygen remarkably enhanced the chlorobenzene conversion and the cooperation catalysis of Hβ zeolite and Ac 2 O envidently improved the selectivity to para -nitro product. Under the optimized reaction conditions, 93.6 % of the selectivity to p -nitrochlorobenzene with 84.0 % of chlorobenzene conversion was obtained, and the ratio of p -nitrochlorobenzene to o -nitrochlorobenzene could reach up to 20.3. Furthermore, the selectivity distribution of nitration products was reasonably explained by the density functional theory (DFT) calculation. Finally, the possible nitration reaction pathway of chlorobenzene with NO 2 was suggested in O 2 -Ac 2 O-Hβ composite catalytic system. The present work affords a new and mild nitration approach for highly selective preparation of valuable para -nitro products, and has potential industrial application prospects.
Deng Renjie,Cui Haishuai,Liu Meilin,Ni Wenjin,Tian Yao,Liu Huajie
Different solid superacid sulfated zirconium dioxide (SO 4 2− /ZrO 2 ) samples were successfully prepared by conventional and ultrasonic-assisted chemical precipitation process, and then, they were characterized by X-ray diffraction, Fourier transform infrared, thermal gravimetric analyzer (TGA), nitrogen adsorption–desorption, ammonia temperature programmed desorption (NH 3 -TPD) and pyridine adsorbs Fourier transform infrared. The results of characterizations indicate that the sulfonic acid group is successfully introduced, and the acidity and surface area of sulfated sample can be increased by using ultrasonic method. Furthermore, this ultrasonic-assisted catalyst was used for the chlorobenzene nitration using nitrogen dioxide (NO 2 ) as nitrating agent. The catalyst shows excellent catalytic activity and reusability for the nitration of chlorobenzene giving high para -selectivity. In the optimal reaction conditions, the conversion of chlorobenzene can reach 85.2% with 88.5% selectivity to para- nitrochlorobenzene ( p -NCB). Furthermore, the reaction mechanism was proposed by combination of experimental results and theoretical calculations. The present work provides an easy-to-implement, mild and environmentally friendly approach for the efficient preparation of valuable p -NCB, which has extensive industrial application prospects. Graphical abstract
Fanyue Meng,Chenbin Lin,Bing Song,Lei Yu,Yan Zhao,Zejian Zhi,Min Song
This study employed a self-designed underwater arc discharge (UAD) plasma reactor, which combined advanced oxidation process (Fe 2 O 3 -CoFe 2 O 4 /PMS) and low-temperature plasma technology to efficiently degrade refractory organic pollutants (i.e. phenol, p-chlorophenol, p-nitrochlorobenzene). The results illustrated that the plasma/PMS/Fe 2 O 3 -CoFe 2 O 4 system possessed high degradation efficiency and TOC removal rate towards three target pollutants (phenol: 99.8%, 96.12%; 4-CP: 98.4%, 86.48%; p-NCB: 99.9%, 88.31%). With the help of in-situ variable temperature EPR and Indigo colorimetry method, ·OH, SO 4 ·- , O 2 ·- , 1 O 2 and O 3 were identified as the main reactive oxygen species (ROS) for the degradation of target pollutants, revealing the synergistic catalytic mechanism between plasma and Fe 2 O 3 -CoFe 2 O 4 for PMS activation and inferring the degradation pathways of target pollutants. The results confirmed that the plasma/PMS/Fe 2 O 3 -CoFe 2 O 4 system was feasible for the degradation of refractory organic pollutants, has the advantages of high efficiency and low energy consumption, and could provide an effective strategy for the treatment of refractory organic pollutants in groundwater/soil.
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